luhn_validator.rb

module LuhnValidator
  # Validates credit card number using Luhn Algorithm
  # arguments: none
  # assumes: a local String called 'number' exists
  # returns: true/false whether last digit is correct
  def validate_checksum
    nums_a = number.to_s.chars.map(&:to_i)

    # TODO: use the integers in nums_a to validate its last check digit
  end
end